Intrinsic Contribution of Perforin to NK-Cell Homeostasis during Mouse Cytomegalovirus Infection

Low Percentage of Perforin-Expressing NK Cells during Severe SARS-CoV-2 Infection: Consumption Rather than Primary Deficiency

Genetic defects in the ability to deliver effective perforin have been reported in patients with hemophagocytic lymphohistiocytosis. We tested the hypothesis that a primary perforin deficiency might also be causal in severe SARS-CoV-2 infection. We recruited 54 volunteers confirmed as being SARS-CoV-2-infected by RT-PCR and admitted to intensive care units or non-intensive care units and age- and sex-matched healthy controls. Compared with healthy controls, the percentage of perforin-expressing CD3-CD56+ NK cells quantified by flow cytometry was low in COVID-19 patients (69.9 ± 17.7 versus 78.6 ± 14.6%, p = 0.026). There was no correlation between the proportions of perforin-positive NK cells and T8 lymphocytes. Moreover, the frequency of NK cells producing perforin was neither linked to disease severity nor predictive of death. Although IL-6 is known to downregulate perforin production in NK cells, we did not find any link between perforin expression and IL-6 plasma level. However, we unveiled a negative correlation between the degranulation marker CD107a and perforin expression in NK cells (r = -0.488, p = 10-4). PRF1 gene expression and the frequency of NK cells harboring perforin were normal in patients 1 y after acute SARS-CoV-2 infection. A primary perforin defect does not seem to be a driver of COVID-19 because NK perforin expression is 1) linked neither to T8 perforin expression nor to disease severity, 2) inversely correlated with NK degranulation, and 3) normalized at distance from acute infection. Thus, the cause of low frequency of perforin-positive NK cells appears, rather, to be consumption.

Case Report: Missing zinc finger domains: hemophagocytic lymphohistiocytosis in a GATA2 deficiency patient triggered by non-tuberculous mycobacteriosis

Haploinsufficiency of GATA2, also known as GATA2 deficiency, leads to a wide spectrum of clinical manifestations. Here we described another 28-year-old man with a GATA2 variant who also suffered from hemophagocytic lymphohistiocytosis(HLH), who was finally diagnosed with HLH triggered by Mycobacterium avium bloodstream infection due to primary immunodeficiency. We reviewed GATA2 deficiency patients with HLH and found that GATA2 variants causing loss of zinc finger domains were associated with HLH, and erythema nodosa might be an accompanying symptom.

Interaction of perforin and granzyme B and HTLV-1 viral factors is associated with Adult T cell Leukemia development

Objective(s):

Human T cell leukaemia virus type 1 (HTLV-1) is associated with adult T cell leukaemia (ATL), a malignant lymphoproliferative disease that infects CD4 T cells. It is not clear why the majority of HTLV-1-infected individuals remain asymptomatic carries (ACs) and a minority develop ATL. Cellular immune response has a critical role in ATL and destroys malignant and HTLV-1-infected cells. Perforin and granzyme have important functional roles in apoptosis and destruction of infected cells. In the present study we examined the role of perforin and granzyme in ATL patients and ACs.

Materials and Methods:

Peripheral blood mononuclear cells (PBMCs) were isolated from ATL patients and ACs by using Ficoll-hypaque density centrifugation. RNA was extracted and cDNA was synthesized. A real-time PCR TaqMan method was designed and optimized for evaluation of perforin, granzyme, tax, and HBZ gene expression. HTLV-1 proviral load (PVL) was quantified in patients with ATL and ACs.

Results:

The mRNA expression of tax and HBZ was significantly higher in ATL patients than ACs (P=0.011 and P=0.0001,respectively). The HTLV-1 PVL was higher in ATL patients compared to with AC group (P=0.015). There was a significant increase in perforin gene expression in ACs compared with ATL patients (P=0.002). Furthermore, the expression of granzyme was also higher in ACs compared with ATL patients, and significant differences were observed between the two groups (P=0.036).

Conclusion:

Low expression of perforin and granzyme in ATL patients seems to influence the efficiency of CTL function and destruction of HTLV-1-infected cells, which might contribute to the disease pathogenesis.